This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A066594 #4 Dec 05 2013 19:55:05 %S A066594 3,11,13,19,31,101,103,109,113,127,131,139,181,191,193,199,271,311, %T A066594 313,331,811,911,919,991,1009,1013,1019,1031,1033,1039,1091,1093,1103, %U A066594 1109,1181,1193,1279,1301,1303,1319,1327,1381,1399,1811,1901,1913,1931 %N A066594 Primes which can be expressed as concatenation of powers of 3 and 0's. %e A066594 271 is a term as it is a concatenation of 27 and 1 which are powers of 3. %Y A066594 Cf. A066591, A066592, A066593. %K A066594 base,easy,nonn %O A066594 1,1 %A A066594 _Amarnath Murthy_, Dec 21 2001 %E A066594 Corrected and extended by Christopher Lund (clund(AT)san.rr.com), Apr 14 2002